FAQ

What is Selective Breeding?

Selective breeding it the process of selecting oysters with desirable qualities, like fast growth, high survival or favorable shell shape, as parents for the next generation. When these traits have a genetic basis, selecting parents with superior performance can increase the likelihood that the next generation will inherit the genes associated with those traits, leading to gradual genetic improvement over successive generations.  This is the same fundamental approach that has been used for decades to improve crops, livestock and even companion animals like dogs and cats, but here we apply it to oysters.  

In selective breeding, we choose oysters based on observable characteristics (their phenotype), such as shell size, meat yield, or survival. Because we know that these traits are influenced by genetics (their genotype), we can expect that, on average, their offspring will also perform better for those same traits. For example, breeding larger, faster-growing oysters together increases the likelihood that the next generation will also grow larger and faster.

What is a triploid/ what are polyploids?

Oysters contain chromosomes, just like humans do, which contain its genetic information. Oysters are diploid (2N), meaning they have two sets of chromosomes—one inherited from each parent.

Polyploid is a general term for organisms with more than two sets of chromosomes. In oysters, the most common polyploids are triploids (3N), which have three sets of chromosomes, and tetraploids (4N), which have four.

Triploid oysters are produced by crossing a diploid (2N) oyster with a tetraploid (4N) oyster. Because they have an odd number of chromosome sets, triploids are typically unable to reproduce normally. In many cases, triploid oysters grow faster than diploids; this is because energy normally used for reproduction can be diverted to growth. In addition, because they do not spawn, they maintain favorable meat quality year-round. Currently, more triploid oysters are grown than diploids for this reason.

Tetraploid oysters are not produced commercially for consumption. At ABC, they are maintained as specialized breeding lines and are used only as parents to produce triploid offspring for commercial aquaculture.

Are polyploids GMO?

A GMO, or genetically modified organism, is by definition an organism that has had its genetic material changed through genetic engineering. Genetic engineering involves modifying the gene sequences or transferring DNA from one organism to another. Agricultural crops are often modified to tolerate weed killers and bacteria are modified to make medical products like insulin.

Polyploid oysters are not genetically modified organisms (GMOs). They do not contain genes from other species or have their DNA artificially altered. Polyploidy simply changes the number of chromosome sets an oyster has—a naturally occurring phenomenon that can also be produced using established breeding techniques.

Polyploidy is common throughout nature and in many foods we eat every day. Bananas are triploid, which is why they produce little or no seed. Many commercial watermelons are also triploid, giving us the familiar seedless varieties. Other crops, including wheat, potatoes, strawberries, and some blueberries, are naturally polyploid. 

What's the difference between spat, seed, broodstock, larvae, etc?

• Larvae are newly hatched oysters that are free-swimming and microscopic. They form about a day after fertilization and already have their shells at this point! They use microscopic hairs called cilia to orient themselves and move in the water and feed on a variety of phytoplankton (algae),  This is the most sensitive stage in oyster development.  Oysters are considered larvae for about 2 weeks, after which point they develop an eye spot (a light sensing organ, not a true eye) and a foot to help them find suitable substrate to attach to.  Once they find a place to settle, which is usually oyster shell, they will metamorphose and become sessile/non-moving as they change into their adult body form.
• Spat and seed are often used interchangeably, but in aquaculture they can describe two different ways of producing and growing juvenile oysters.
  • Spat generally refers to oysters that have completed metamorphosis and settled onto a solid surface, typical larger pieces of oyster shell. Hundreds or even thousands of young oysters may settle onto a single piece of shell, creating what is commonly called spat-on-shell. This type of spat is often used to establish or restore oyster beds and reefs in creeks, rivers, and coastal waters. The term spat is also commonly used for juvenile oysters that settle naturally in the wild.
  • Seed refers to young oysters that are produced as individual, loose oysters rather than attached to a larger piece of shell or cultch. Hatcheries can produce single oysters by allowing larvae to settle onto very small particles of ground up oyster shell called cultch, often no larger than a grain of sand. As the oyster grows, the tiny piece of cultch becomes incorporated into the oyster's shell, resulting in a single, easily handled oyster.  Single-oyster seed is especially useful in aquaculture because each oyster can be grown and managed individually. This makes it well suited for farm production, where oysters are grown to market size, as well as for selecting and maintaining individual oysters as broodstock. The term “seed” comes from the idea of seeding an oyster farm or bed—young oysters are the starting material for producing the next crop, much like seeds are planted to produce an agricultural crop. 

• Broodstock are mature, adult oysters selected to serve as parents for producing the next generation. Rather than being grown for harvest, broodstock are chosen for desirable traits—such as growth, survival, disease tolerance, or shell shape—and used to produce the next generation of oysters. By carefully selecting which oysters become parents, selective breeding can increase the likelihood that desirable traits will be passed on to their offspring.

How can I buy your oysters?

In short- you cant!  ABC produces our oysters specifically for distribution to commercial hatcheries who then use them to produce more oysters.  We distribute them under a licensing agreement, a legal contract, that allows the hatchery to utilize ABC’s intellectual property. Hatcheries condition and spawn our broodstock oysters, sell the eyed larvae or seed or keep them to sell as market oysters. In many cases, oysters you find at a restaurant may come from our commercial hatchery partners, but they will always be a second generation, not direct from ABC. 

 If you are a commercial hatchery interested in utilizing our diploid or tetraploid broodstock lines, please reach out to our Broodstock Manager, Nate Geyerhahn, to discuss the licensing agreement and learn more about our lines.   If you want to know how you can support our industry partners and purchase oysters from them, please visit the industry partners page

What is the difference between the different oysters you offer? 

ABC produces both diploid (2N) and tetraploid (4N) oysters for distribution.  Each line that we make is grown out in specific environments with variable disease and salinity pressures, which results in lines being selected for specific environments.  You can find even more detail about this on our broodstock offerings page

Are all of your lines disease resistant?

Disease resistance is the ability of an oyster to reduce infection by a pathogen. Disease tolerance is the ability of an oyster to remain healthy and survive despite becoming infected. In practice, oysters selected for disease resistance often exhibit a combination of both traits, making them more likely to survive in areas where diseases such as Dermo or MSX are common.

Not all of our lines are specifically selected for disease resistance.  For example, LILY and LOLA are grown out and specifically selected to perform well in low salinity sites where stress from freshets and low salinity can be problematic.  Dermo typically is not observed in lower salinity sites where these lines are selected  (below 12-15 ppt), thus they do not regularly experience disease pressure compared to our other moderate salinity test sites. As such, lines like LILY and LOLA are not specifically selected for disease resistance and are not expected to handle disease pressure as well as some of our other lines might. 

It's important to remember that no oyster line is completely immune to disease. When we describe a line as "disease resistant," we mean that the line has demonstrated better survival under disease pressure than unselected populations. Individual oysters within the line can still become infected or succumb to disease, and performance will vary depending on environmental conditions, disease intensity, and the genetics of each individual oyster.